Xinjiang's bloody Sunday explosion of violence in Urumqi has underscored the struggle of ethnic minorities to find a place in a modernising China and a homogenising world.

As in Lhasa last year, a peaceful protest suddenly became a murderous race riot. Then, it was indigenous Tibetans beating Han and Hui settlers to death, destroying their shops and cars. This time, it appears to be mainly Uighurs.

Then, as now, Beijing blamed exile leaders for orchestrating the unrest. First the Dalai Lama, now Rebiya Kadeer, of the World Uighur Congress.

The counter-accusations are also similar. Uighur exiles accuse the security forces of provoking violence by killing protesters and fostering resentment with tight restrictions on religious, cultural and political autonomy. In both cases the outside world's views have been obscured, partly because of Chinese restrictions on the media and partly because of the sheer distance of the two areas from the industrialised world. Buddhist Tibetans and Muslim Uighurs share a similar predicament.

While most of the world industrialised, their two regions remained islands, falling behind economically and politically, while maintaining a strong cultural and religious identity.

They were never completely remote. Major Francis Younghusband's murderous invasion of Tibet is one of the darkest episodes of British imperialism. Mao Zedong went further in 1949 by ordering the People's Liberation Army into Xinjiang (which means New Frontier) and Tibet. This year the authorities are celebrating the 60th anniversary of what the state media often refers to as the "peaceful liberation". For exile groups, it was simply an invasion.

Until 60 years ago Beijing ruled the country's fringes with a distant hand, largely because access was difficult and the economic benefits questionable. That has changed dramatically with the rise of Chinese power and globalising technology. Roads, railways and airports put Lhasa and Urumqi within easy reach of Beijing. The country needs Tibet's water and Xinjiang's oil and gas.

Beijing has strengthened its grip with a programme of rapid economic development, tight controls on religious belief, a big military presence and an influx of Han and Hui migrants. These ethnic groups are now the majority in the capitals of Tibet and Xinjiang and appear to gain most of the economic benefits. Two of the sparks for the latest unrest were the demolition of the old Uighur capital in Kashgar and the killing of two Uighur migrants by a mob of Han in Shaoguan, on the other side of China.

The fear now is that racial violence is intensifying. The biggest difference between the riots in Tibet and Xinjiang is the death toll. According to government figures 156 died in Urumqi, more than seven times as many as in Lhasa. These figures, like the causes of the riots, are disputed, but clearly a long simmering problem has reached boiling point. "There is no justification for ethnically targeted violence, but this calls into question how effective the central government's policies have been towards minorities," said Nicholas Bequelin of Human Rights Watch. "These riots will have a long-lasting impact on already bad ethnic relations in Xinjiang."

China needs to rethink its approach to the ethnic issue. As with all nations that pioneered "new frontiers", the adjustment is likely to be painful.